1 files changed, 77 insertions, 0 deletions
diff --git a/third_party/rust/zerocopy-derive/tests/union_unaligned.rs b/third_party/rust/zerocopy-derive/tests/union_unaligned.rs
new file mode 100644
index 0000000000..5ba3ac76ac
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+++ b/third_party/rust/zerocopy-derive/tests/union_unaligned.rs
@@ -0,0 +1,77 @@
+// Copyright 2019 The Fuchsia Authors
+//
+// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+#![allow(warnings)]
+
+use std::{marker::PhantomData, option::IntoIter};
+
+use {static_assertions::assert_impl_all, zerocopy::Unaligned};
+
+// A union is `Unaligned` if:
+// - `repr(align)` is no more than 1 and either
+//   - `repr(C)` or `repr(transparent)` and
+//     - all fields `Unaligned`
+//   - `repr(packed)`
+
+#[derive(Unaligned)]
+#[repr(C)]
+union Foo {
+    a: u8,
+}
+
+assert_impl_all!(Foo: Unaligned);
+
+// Transparent unions are unstable; see issue #60405
+// <https://github.com/rust-lang/rust/issues/60405> for more information.
+
+// #[derive(Unaligned)]
+// #[repr(transparent)]
+// union Bar {
+//     a: u8,
+// }
+
+// is_unaligned!(Bar);
+
+#[derive(Unaligned)]
+#[repr(packed)]
+union Baz {
+    // NOTE: The `u16` type is not guaranteed to have alignment 2, although it
+    // does on many platforms. However, to fix this would require a custom type
+    // with a `#[repr(align(2))]` attribute, and `#[repr(packed)]` types are not
+    // allowed to transitively contain `#[repr(align(...))]` types. Thus, we
+    // have no choice but to use `u16` here. Luckily, these tests run in CI on
+    // platforms on which `u16` has alignment 2, so this isn't that big of a
+    // deal.
+    a: u16,
+}
+
+assert_impl_all!(Baz: Unaligned);
+
+#[derive(Unaligned)]
+#[repr(C, align(1))]
+union FooAlign {
+    a: u8,
+}
+
+assert_impl_all!(FooAlign: Unaligned);
+
+#[derive(Unaligned)]
+#[repr(C)]
+union TypeParams<'a, T: Copy, I: Iterator>
+where
+    I::Item: Copy,
+{
+    a: T,
+    c: I::Item,
+    d: u8,
+    e: PhantomData<&'a [u8]>,
+    f: PhantomData<&'static str>,
+    g: PhantomData<String>,
+}
+
+assert_impl_all!(TypeParams<'static, (), IntoIter<()>>: Unaligned);